Mucins have been implicated in the pathogenesis of benign and malignant diseases of secretory epithelial cells; however, the molecular basis of the alterations that occur in mucins during different diseases is poorly understood. We cloned a mucin gene from a cDNA library prepared from the human pancreatic tumor cell line HPAF, that showed identity to the published partial sequence of MUC4 cDNA. MUC4 showed differential and regulated expression in several pancreatic tumor cell lines but undetectable expression in normal pancreas. This leads us to propose the hypothesis that MUC4 expression is involved in the general pathogenesis and metastatic spread of pancreatic adenocarcinoma. The objectives of this proposal are to define the structure and regulation of human MUC4 apomucin gene. The recently derived cDNA fragments will be used to isolate the full-length cDNA and regulatory sequences for the MUC4 gene. Specifically, we propose to: 1) Clone and characterize the full-length MUC4 cDNA. The cDNA and gene containing MUC4 coding and regulatory sequences will be cloned and characterized. 2)Investigate the role of regulated expression of MUC4 in human pancreatic tumor cells. Pancreatic cell lines expressing regulated levels of MUC4 will be used as a model to evaluate the role of growth factor(s) in regulating MUC4 expression. The effects of MUC4 expression on the growth kinetics, metastatic properties and morphology of the MUC4 cDNA transfected cells will be investigated. 3) Generate and characterize monoclonal antibodies to the recombinant MUC4 protein and cell lines expressing transfected cloned MUC4 cDNA. Antibodies will be characterized for specificity for mucins, affinity for the antigen and reactivity against Pancreatic tumor cells. The proposed studies will determine the structure and function of the MUC4 mucin in general and may define a role for MUC4 in the pathogenesis of human pancreatic neoplasia. Characterization of this gene and its product will aid in the development of probes and antibodies that may be useful for diagnosis and treatment of pancreatic adenocarcinomas.